18.1 Disk Devices and Their Configuration | HP Certified: HP-UX System Administration

Every physical disk has two device files associated with it. These device files are used for disk I/O activities. One of these is the raw device file and the other is the block device file. Each disk must be configured before it can be used with HP-UX. A disk may be subdivided and each of these subdivisions used for a specific purpose. A disk may be subdivided in such a way that a subdivision contains all the available space on the disk or only a part of it. The boot area is a special subdivision that contains utilities and files used at boot time, as you have seen in Chapter 14. Other than that, a subdivision may be utilized for one of the following.

A file system that contains an area for storing files. Examples of this type of area are /usr , /var , and /home . Each of these is used for storing a particular type of file.
A swap area used for swap space. Swap space is used in place of physical memory when the system needs more memory than what is installed in the system. It is also used for crash dumps. The size of swap space must be larger than the physical memory for a successful dump creation.
A storage location for raw data, such as might be used by Sybase, Informix, Oracle, or other database products.

Other than these two types of areas, databases also use raw data areas that can be directly accessed by a database.

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